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We have applied one-dimensional (1D)  1 H MAS NMR,  27 Al →  1 H CP MAS NMR, as well as 2D  27 Al triple-quantum (3Q) MAS NMR,  27 Al →  1 H heteronuclear correlation (HETCOR) and high-resolution 3QMAS/HETCOR NMR techniques to KAlSi 3 O 8  (Or), NaAlSi 3 O 8  (Ab) and NaAlSiO 4  (Ne) glasses containing 0~2 wt% H 2 O to shed light on the dissolution mechanisms of water in aluminosilicate melts (glasses). An Al Q 3 -OH group, characterized by  1 H chemical shifts of 1.3-1.9 ppm, was identified for all hydrous glasses. Its abundance increases with bulk Al/Si ratio. The  27 Al chemical shifts (δ i  Al ) of this species are 64-68 ppm, larger than those of Al Q 4  by 3-6 ppm. Despite this difference, it is only through  27 Al →  1 H HETCOR and 3QMAS/HETCOR, but not  27 Al MAS or 3QMAS NMR that the peaks are resolved. This study has demonstrated that depolymerization and formation of AlOH/SiOH is a general water dissolution mechanism for polymerized aluminosilicate melts (glasses), and HETCOR NMR experiments involving  1 H are the key to its revelation.

Depolymerization effect of water in aluminosilicate glasses: Direct evidence from 1 H- 27 Al heteronuclear correlation NMR